The aim of this annual report is to present an updated assessment of the threat that non-state actors pose through the use of chemical, biological, radiological, or nuclear (CBRN) agents to create adverse effects on society. The content is based solely on open-source information and includes a selection of incidents that occurred in 2021. The report has been produced by a research group at FOI (Swedish Defence Research Agency), within the framework of a grant from the Swedish Ministry of Defence. No known CBRN-related terrorist attack has occurred during 2021. However, there is still widespread concern that this type of attack, with its societal consequences, can still occur. Expressions of threats and the issuing of propaganda and instructions for carrying out CBRN attacks continue to be disseminated within violent extremist communities, for the purpose of spreading fear and inspiring sympathisers to take action. Propaganda and the expression of threats during this year have largely been influenced by the ongoing pandemic of COVID-19 and its effects and consequences.